Pitch differential means for lifting propellers



June 23, 1936. R. R. HAYS 2,045,355

' PITCH DIFFERENTIAL MEANS FOR LIFTING PROPELLERS Filed April 27 l935 2Sheets-Sheet l INVENTOR Passe Hays June 23, 1955 R R. HAYS 2,045,555

PITCH DIFFERENTIAL MEANS FOR LIF'IING PROPELLERS FIG. 4

INVENTO/f /?usse R. Hays dam A TTORNE V Patented June 23, 19 36.

UNITED STATES PATENT OFFICE PITCH'DIFFERENTEAL MEANS FOR LIFTINGPROPELLERS 7 Russell R. Hays, Encinitas, Calif.

Application April 27, 1935, Serial No. 18,648

20 Claims. (01.170-162) My invention, relates to means for varying thepitch of blades of lifting propellers at difierent moments of rotation,more particularly to'means of eifecting such variation by reason of thedrag dissymmetry.

In testing articulative blades which are so mounted that variation intheir lift and centrifu- First, to providea hinged mounting for theblades of a lifting propeller whereby they are free to oscillate withintheir plane'of rotation andin which said oscillation automaticallyproduces a change in their pitch;

' Second, to provide a yieldable mounting for articulativeblades of arotating blade structure whereby the drag of the opposed blades ismomentarily balanced across the axis of rotation and movement'of thispoint of balance away from the axis of rotation produces a decrease inthe pitch of one blade and an increase in the pitch" of the oppositeblade;

Third, to provide a hinged mounting for blades of thisclass in which thedrag dissymmetry produces a dissymmetry of the blades in plan form witha consequent movement of the blades in planes perpendicular tothe planeof rotation;

Fourth, to provide a hinged mounting for propeller blades which permitsarticulation of the blades within and at right angles to their plane ofrotation, such articulation not being directly responsive to the drivingtorque;

Fifth, to, provide a hinged mounting for articulative blades of arotating blade structure whereby the blades are free-to oscillate withintheir plane of rotation which results in a feathering action of theblades, such oscillation being inde; pendent mechanically of theoscillation perpendicularly to their, plane of rotation, which alsoproduces a feathering reaction of the blades;

Sixth, to provide a means that is automatically operative in case ofengine failure to convert a lifting propeller having the foregoingcharacteristics into an auto-rotative blade structure of the gyrcplanetype;

, Seventh,- to provide a means of this class which will reduce to aminimum the usual extreme Fig. 3 is a diagrammatic plan view of apropeller pitch variation occurring by reason of the movewill reduce toa minimum the vibration in the operation of propeller blades of thisclass;

Eighth, to provide a means of this class which stresses in. connectionwith propeller blades of this class; and

Ninth, to provide a means of this class which is very simple andeconomical of construction, eificient in its action, durable, and whichwill not readily deteriorate or get out of order.

With these and other objects in view as will appear hereinafter, myinvention consists of certain novel features of construction,combination and arrangement of parts and portions as will be hereinafterdescribed in detail and particuflarly set forth in the appended claims,reference being had to the accompanying drawings and to the charactersof reference thereon which form a part of this application, in which: t

Figure 1 is a side elevational view of my differential hinge structureshown in connection with afragmentary portion of the propeller bladesand] showing the varying axial lines diagrammatically; Fig. 2 is a topor plan view of the same;

differentially mounted showing the varying positions of the bladesresultant to drag dissym-' 'metry; Fig. 4 is a diagrammatic sectionalview taken along the line 4-4 of Fig. 3 illustrating the ment of theaxes of the differential, and Fig. 5

is a diagrammatic view. showing thelimitation of the coning angleresultant to engine failure whereby the propeller is converted into anautorotative blade system.

Similar characters of reference refer to similar .parts and portions anddiagrammatic relation throughout the several views of the drawings.

Referring to Figs. 1 'and 2 of the drawings, there is provided a driveshaft I which is rigidly 40 secured to a head bracket member 2 by meansof a reduced portion 20. extending through a, conforming hole in themember 2 and upon which is mounted a nut la. This bracket 2 is providedwith upwardly extending journal portions 2b in which are mounted journalbolts 3 which may be tap bolts rigidly screwed into the differentialbracket 4 which difierential bracket is free to rotate about a mainhorizontal axis 3-3 to the center of the journal bolts 3, said axis B-Bbeing at right angles to and intersected by the axis AA of the driveshaft I. This differential bracket 4 is substantially a rectangularpiece 'of metal, the shorter axis: of which coincides with the axis A-Apf rotation, and the longer axis. of

which is intersected by and makes an acute angle equal to the value ofY, as shown in Fig. 2, with the axis BB rearwardly to the propellersdirection of rotation'R. Each of the corners of the rectangular bracketmember 4 carries a journal bolt 5 alined with the diagonals of therectangle and comprises axes CC and D--D for the hinge members 8 and 9which are held by the hangers 1 and 6, respectively. The axes 0-0 andD.D make acute angles Y with the main horizontal axis BB rearwardly anddownwardly. The outer ends of the hinge members 8 and 9 extend from theupper hangers and are secured to the propeller blades [0 and II in sucha manner that the longitudinal axes E-Eof the blades form an acute angleX with the axes CC and DD downwardly and forwardly. Consequently theblades l0 and l I are free to rotate about the axes CC and D-Ddownwardly. until the hinge members contact the diiferential bracket 4,and upwardly until their movement is arrested at auto-rotative attackangles by reason of the projections I2 on the hinge members'a and 9contacting the differential bracket 4, shown best in Fig. 1 of thedrawings.

It will be here noted that all the parts and portions are symmetricallydisposed and the posi-' tioning of the blades l0 and II issuch that theyhave an effective attack angle when in equilibwhere the inflow of air isuniform the equilibrium of the blades will remain constant and hencethere will be no oscillation. However, with translation, the inflowceases to be uniform and consequently the lift on the blade advancing inthe direction of the air motion increases, whereas that on theretreating blade decreases. When this occurs the consequent movement ofthe blade is about the axis BB rather than either the axis CC or D-Dsince the lift L of the blades, shown best in Fig. 4, has a more nearlyvertical component L' and hence'leverage effect to the axis BB, than thecomponent L" to the axis CC. Therefore, since the longitudinal axis EE(see Fig. 3) of the blade has a sweepback angle Z to the axis BB in planform, Fig. 3, a feathering action results as is well known in the artwith a consequent tilting of the plane of rotation P-P, Fig. 4.Simultaneously with the creation of such feathering action thedifferential bracket 4 becomes efiective. The primary reaction is thatdue to feathering the drag on the blades at rearward moments of rotationbecomes greater than the drag at forward moments, hence destroying theequilibrium relative to the center point of th differential bracket andconsequently producin rotation of the bracket in the direction of. therearwardly working blade.

With such rotation of the differential bracket, the axes CC and D-Ddescribe a conical path about the axis BB in opposite directionsrelatively to the direction of rotation of the attached blades Ill andII. At the same time the longitudinal axes -EE of the blades havingsweepback to the axes CC and D-"-D also describe conical pathsrelatively to the latter. Due to the fact that the blades are held intheir plane of rotation by lift and centrifugal forces and sincemovement at right angles to the lift is confined to this plane, it willbe seen that rearward movement of the blade, Fig. 3, produces rotationof the axis CC about axis BB along a path M Fig. 4 to a point C'C' andat the same time a counter rotation of the blade axis E-E about the axisCC along a path N which has moved back to the position N with aconsequent decrease in pitch. At the same time the reverse rotation ofaxes takes place onthe opposed blade with resultant increase in pitch.

The secondary reaction of the differential bracket results from the factthat'by this arrangement of axes rearward movement of one blade producesa corresponding forward movement of the opposite blade, thus the angleZ, Fig. 3, increases to Z on the rearwardly working blade, whereas theangle Z decreases to Z" on the forwardly working blade. Consequently thelift L of the former blade has a greater leverage effect relatively tothe axis BB than the lift on the latter, thereby producing rotation of kthe propeller about the axis BB with a resultant decrease in the pitchof the rearward blade and an increase of the pitch in the forward blade.

Inasmuch as the greatest lift dissymmetry on a lifting propeller intranslation occurs at lateral moments of rotation, whereas the greatestdrag dissymmetry occurs at longitudinal moments of rotation, and sinceas a result of lag, means responsive to either dissymmetry persist overa quarter of a revolution, it is readily apparent that pitchvariationwhich anticipates airflow variation will greatly reducepitching and rolling moments of the propeller as well as increase itsefficiency. In the case of engine failure and-with the use of anover-running clutch as is conventional in the art, the equilibrium ofthe blade changesthereby increasing its coning angle. Withthe use ofsmall values of angles X, Figs. 1 and 2,.

such an increase in the propellers coning angle throws the pitch intoextreme negative angles, :therefore theprojections l2 on the hingemembers 8 and 9 are utilized to restrict this coning at A a point givingan eifective auto-rotative pitch setting of the blades. Thus as shown inFig. 5, the normal coning pitch J-J of the blades would tend to increaseto K--K but is restricted at the position H-H. This in efl fect locksthe action of the differential bracket as responsive to the drag'dissymmetry and consequently the propeller is automatically converted toa rigid blade structure of the gyroplanetype as is well known to theart. From the foregoing description it will be seen that I have provideda selective differential for an articulative blade of'a rotating bladestructure whereby variation of the airflow encountered by the blade atdifferent moments of rotation produces rotation of the elements aboutthree separate axes. It isobvious that sucha means is ,capable of broadmodification, as for instance, a

. rearrangement of the three axes'to permit the use claim as new'anddesire to secure by Letters Patent is:

1. In a pitch differential means for lifting propellers, a main bracketmember provided with a main horizontal axis and axes at acuteanglesthereto.

2. In a pitch differential means for lifting propellers, a main bracketmember provided with a main horizontal axis and with axes at acuteangles thereto, a journal bracket journaled on said main bracket memberat the main horizontal axis thereof. I

3. In a pitch difierential means for lifting propellers, a main bracketmember provided with a main horizontal axis and with axes at acuteangles thereto, a journal bracket journaled on said main bracket memberat the main horizontal axis thereof, and propeller blades mounted onsaid acute angle axes in opposed relation to each other.

4. In a pitch differential means for lifting propellers, a main bracketmember provided with a.

main horizontal axis and with axes at acute an-y gles thereto, a journalbracket journaled on said main bracket member atthe main horizontal axissaid main bracket member to limit the feathering action of said blades.

6. In a device of the class described, a main bracket member providedwith a central normally horizontal axis and with a plurality ofaxes-intersecting said central axis at acute angles to each' other.

'7. In a device of the class described, a main bracket member providedwith a central normally horizontal axis and with a plurality of axesintersecting said central axis at acute angles to each other, means forsupporting said main bracket member on a normally horizontal axis.

8. In a device of the class described, amain bracket member providedwith a central normally horizontal axis and with a. plurality of axesintersecting said central axis at acute angles to each other, means forsupporting said main bracket member on a normally horizontal axis,propeller blades pivotally mounted on said second mentioned axes inopposed relation to each other.

9. In a rotative blade, structure for aircraft, means for universallymounting the blades comprising a plurality of axes, one of which "isfixed inits position relative to the axis of rotation of the structure,and a bar journaled for movement about the first axis carrying a. secondaxis on which is pivotally mounted the blade.

10. In a rotative blade structure for aircraft, means for universallymounting the individual blades comprising a plurality of axes forwardlydisposed to the blade, one of which is fixed relative to the axis ofrotation, a bar iournaled for movement about the first axis carrying asecond axis to which is hinged the blade, this axis lying between thefirst axis and the longitudinal axis of the blade, and making an acuteangle with the plane defined by the last two axes.

11. In a rotative blade structure for aircraft, means for differentiallymounting the blades comprising a plurality of axes, a fixed axisforwardly disposed to the lift line ofthe blades providing a pivot forsimultaneous movement of opposedv blades at right angles to their planeof rotation, a bar pivoted to the fixed axis and carrying symmetricallydisposed axes to which are pivotally mounted opposite blades.

12. In a rotative blade structure for aircraft, means for differentiallymounting the blades comprising a plurality of axes, a fixed axisforwardly disposed to the lift line of the blades providing a pivot forsimultaneous movement of opposed blades at right angles to their planeof rotation, a bar pivoted to the fixed axis and carrying symmetricallydisposed axes to which are pivotally mounted opposed blades, theselatteraxes making acute angles with each other, with the fixed axis, andwith the longitudinal axes of the attached blades.

13. In a rotating blade structure for aircraft, means comprising aplurality of oblique axes for universally mounting the individual bladesfor simultaneous movement in a plane at right angles to articulativemovement of the blades.

14. In a rotative blade structure for aircraft, means for universallymounting articulative blades comprising a plurality of oblique axesvertical planes through which make acute angles.

15. Ina rotative bladestructure, for aircraft, means for differentiallymounting articulative blades comprising a plurality of oblique axesvertical planes through which-make acute angles.

16. In a rotative blade structure for aircraft, means for universallymounting articulative blades comprising a plurality of oblique axes, anddifferential means responsive to the first means.

17. In a rotative blade structure for aircraft, means for universallymounting articulative blades comprising a plurality of oblique axesvertical planes through which make acute angles, differential meansresponsive to the first means.

18. In a rotative blade structure for aircraft,

means for universally mounting theindividual blades comprising aplurality of oblique axes forwardly disposed to the lift line of theblade relative to its direction of rotation.

19. In a rotative blade structure for aircraft, means for universallyinounting the blades comprising aplurality of oblique axes forwardlydisposed to the center of pressure of the blade, means arranged forrelative movement of these axes coincident with fore and aft movement ofthe blade within its plane of rotation.

20. In a rotative blade structure for aircraft,

means for differentially mounting the blades comprising a plurality ofoblique axes, and means operative to rotate the blades about theirlongitudinal axes with relative fore and aft movement within their planeof rotation.

RUSSELL R. HAYS.

